Marked orthodonic aid and method of manufacturing

ABSTRACT

In order to so improve a metallic orthodontic aid having an optically visible marking area that the marking is easy to apply and is also visible up to a definable number of recycling process cycles, it is proposed that the marking area be a surface of an additionally produced layer with a remelt structure.

This is a continuation of copending application(s) Ser. No. 07/348,039,filed on Apr. 13, 1989, now U.S. Pat. No. 5,238,402.

Field of the Invention

The invention relates to a metallic orthodontic aid with an opticallyvisible marking area.

Background of the Invention

The invention further relates to a method of applying to metallicorthodontic aids surface marking areas which are optically visible.

On metallic orthodontic aids such as, for example, brackets, bands,buccal tubes etc., it is necessary to apply markings in order to clearlyidentify their orientation and allocation to individual types of teeth.

So far it is known to mark such orthodontic aids by, for example, alayer of color being applied or a mechanical identification, forexample, in the form of a notch, being produced in the region of themarking area.

After use, the orthodontic aids may be made fit for use again byrecycling processes. In these recycling processes, firstly the adhesiveby means of which these were attached to the teeth is burned off, forexample, pyrolitically, and secondly the entire orthodontic aid issubjected, for example, to electrolytic surface treatment in order toreproduce the original shining surface.

When orthodontic aids with color markings are subjected to such arecycling process, these color markings are later no longer visible.This has the advantage that it is proof that this aid has been subjectedto a recycling process but also the disadvantage that this orthodonticaid then no longer bears any kind of identification and hence is nolonger clearly identifiable.

The markings in the form of mechanically produced identificationswithstand one or even several recycling processes but from these it isnot possible to ascertain whether the respective orthodontic aid wassubjected to a recycling process or not.

Furthermore, the markings in the form of mechanically producedidentifications have the disadvantage that in comparison with colormarkings, they require a great deal of machine expenditure duringmanufacture.

SUMMARY OF THE INVENTION

The object underlying the invention is, therefore, to so improve anorthodontic aid of the generic kind that the marking is easy to applyand is also visible up to a definable number of recycling processcycles.

This object is achieved in accordance with the invention with anorthodontic aid of the kind described at the beginning by the markingarea being a surface of an additionally produced layer with a remeltstructure.

A layer with a remelt structure within the meaning of the inventivesolution is to be understood as a layer in the metallic aid which isproduced by melting a surface region of a molded or reshaped orotherwise manufactured metallic aid and the metallographic structure ofwhich differs from the structure of the original metallic aid.

Such a layer with a remelt structure has the advantage of not becomingdetached during the individual recycling process cycles but of beingworn away substantially to the same extent as the remaining surface ofthe orthodontic aid. On the other hand, such a layer with a remeltstructure can be produced with a defined thickness and, therefore, thenumber of recycling process cycles which this layer is to withstand canbe fixed by the thickness of the layer with a remelt structure.

Particularly in view of manufacturing simplicity, it is advantageous forthe layer with a remelt structure to be formed from the material of theorthodontic aid so application of an additional material can bedispensed with and only the orthodontic aid itself must undergo melting.

In order to make the optical difference from the remaining surfaceregions of the orthodontic aid particularly distinct, it has provenuseful for the layer with a remelt structure to be roughened on thesurface and, in particular, the layer with a remelt structure isconceived of as exhibiting a crater-like surface.

Furthermore, a distinct optical difference from the remaining surfaceregions of the orthodontic aid is achievable by the layer with a remeltstructure exhibiting reaction products of the metal with an ambientmedium. In the simplest case, these reaction products are metal oxideswhich result from the layer with a remelt structure being produced inthe presence of air. On the other hand, it is, however, also possible toproduce the layer with a remelt structure in the presence of other mediaand to thereby achieve an even more characteristic tempering colorcaused by the respective reaction products.

As previously stated above, the layer with a remelt structure offers thepossibility of fixing the number of recycling process cycles withstoodby the marking by variation of the thickness.

Accordingly, in the simplest case, provision is made for the layer witha remelt structure to exhibit a constant thickness, i.e., penetrationdepth, into the respective surface region of the orthodontic aid. Inthis case, the number of recycling process cycles after which the layerwith a remelt structure is worn away is fixable by the thickness alone.

It is, however, likewise possible for the layer with a remelt structureto exhibit a defined variable thickness so that, for example, after eachprocess cycle the marking area becomes smaller due to worn away portionsof the layer with a remelt structure and hence the number of processcycles through which such an orthodontic aid has already gone isprovable.

Furthermore, it is likewise possible for the layer with a remeltstructure to exhibit a step-wise varying thickness so the marking areabecomes smaller by a previously determinable region after, for example,one recycling process cycle.

In all of these embodiments relating to the thickness of the layer witha remelt structure, provision is made within the scope of the inventivesolution for the thickness to be a multiple, in particular, an integralmultiple of a layer of material worn away from the surface of theorthodontic aid in one recycling process cycle.

A further object underlying the invention is to provide a method whichis as simple as possible for applying optically visible marking areas ofthe generic kind.

This object is achieved in accordance with the invention in a method ofthe kind described at the beginning by a layer with a remelt structurebeing produced in the region of the marking area.

This layer with a remelt structure could be produced by, for example,applying prior to the melting procedure an additional material whichthen unites by means of the melting with a surface of the orthodonticaid. It is, however, considerably easier for the layer with a remeltstructure to be produced by surface melting of the aid so no additionalapplication of material is required and the aid having, for example,polished surfaces, is only melted in that region in which the markingarea is to be produced.

In particular, in order to improve the optical differentiation of such alayer with a remelt structure from the remaining surface of the aid itis advantageous for the layer with a remelt structure to be produced bymelting which differs in intensity from point to point, thereby furtherincreasing the surface roughness in the region of the melting.

In the inventive method, it has proven particularly advantageous for thelayer with a remelt structure to be produced by a laser beam or anelectron beam or a microplasma because all possible forms of markingsare producible in a simple manner with these and, in addition, these arebest suited for manufacturing layers with a remelt structure havingdefined thicknesses.

In order to achieve an optical difference which is as clearly visible aspossible between a polished surface of the orthodontic aid and the layerwith a remelt structure, it has proven advantageous for the layer with aremelt structure to be produced in the presence of a medium which reactswith the metal so a special color can be imparted to it by appropriatechoice of medium. In the simplest embodiment of this method, the layerwith a remelt structure is produced in the presence of air so the metalreacts with the air and the reaction products exhibit the typicaltempering colors known from incandescence.

As previously stated in conjunction with the advantages of the inventivemethod, the latter provides the possibility of producing markings whichare not worn away to a stronger degree than the remaining surface of theorthodontic aid in the individual recycling process cycles. For thisreason, it is advantageous within the scope of the invention for thelayer with a remelt structure to be produced with a thickness which is amultiple, in particular, an integral multiple of the layer thicknessworn away in one recycling process cycle.

Hence it is, for example, possible with a layer with a remelt structurehaving a constant thickness to select it such that it is completely wornaway and thus no longer visible after one or after several recyclingprocess cycles.

With a layer with a remelt structure having a varying thickness, it is,however, also possible for the marking area to decrease in size aftereach recycling process cycle in accordance with the completely worn awayportion of the layer with a remelt structure so each individual markingcycle is thereby provable. In this connection, it is particularlyadvantageous for the layer with a remelt structure to be produced withstep-wise increasing thickness, with the change in thickness in the caseof one step corresponding to the layer thickness worn away in onerecycling process cycle so the marking area becomes smaller in astep-wise manner after each recycling process cycle.

The inventive method can, however, also be used with advantage toproduce a marking which withstands all of the recycling process cyclesto which an orthodontic aid can be subjected within the scope of itsservice life. Here, too, the advantage that layers with a remeltstructure having a defined thickness are producible with the inventivemethod has a positive effect because, in this case, the thickness of thelayer with a remelt structure may be selected such that it is larger inall regions than the sum of the layer thicknesses worn away in recyclingprocess cycles during the service life of such an aid so the markingarea continues to have the same size after each recycling process cycle.

DESCRIPTION OF THE INVENTION

Further features and advantages of the invention are the subject of thefollowing description and the drawings of some embodiments. The drawingsshow:

FIG. 1 a perspective view of a first embodiment of an aid;

FIG. 2 a section along line 2--2 in FIG. 1; and

FIG. 3 a section similar to FIG. 2 in a second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A first embodiment of an inventive aid designated in its entirety 10 inFIG. 1 comprises a bracket 11 the base of which is welded to a retentionbase 12. The bracket 11 is normally profiled, the type of profileapparent from FIG. 1 being typical. Longitudinal grooves 16 andtransverse grooves 18 are usually disposed in such a bracket profile.This results in small areas on the front sides 20, 22 facing away fromthe base 14 with markings 24, 26 disposed on them. Markings in theregion of the transverse groove 18 are likewise possible.

These point-type markings 24 and 26, respectively, as shown in sectionin FIG. 2, are layers with a remelt structure 28 and 30, respectively,which extend with a thickness d from a surface 32 and 34, respectively,of the respective front side 20 and 22, respectively, in the directionof the retention base 12 into the bracket 11. In the region of theselayers with a remelt structure 28 and 30, respectively, the metal fromwhich the bracket 11 is made was heated above the melting point by alaser beam so the structure, for example, when heated in air, exhibitsthe tempering color which is characteristic of the metal heated toincandescence and which results from the chemical reaction of the metalheated above the melting point with the air. Furthermore, a surface 36and 38, respectively, of the layer with a remelt structure 28 and 30,respectively, is no longer smoothly polished like the surfaces 32 and34, respectively, of the front sides 20 and 22, respectively, but rough,which is achievable, for example, by the laser beam being moved over thesurface in a grating-type manner during manufacture of the layers with aremelt structure 28 and 30, respectively.

The thickness d of the layer with a remelt structure 28 and 30,respectively, depends on the energy supplied in point-type configurationto the respective surface region upon which the laser beam impinges.Accordingly, greater laser beam energy or longer dwell time of the laserbeam on the respective point results in a greater thickness d of thelayer with a remelt structure and the latter, therefore, extends furtherinto the interior of the respective bracket wing 16 and 18,respectively.

In the embodiment illustrated in FIG. 2, the thickness d is chosenconstant across the entire layer with a remelt structure 28 and 30,respectively, and, therefore, when surface wearing-away of the layerwith a remelt structure 28 and 30, respectively, occurs in conjunctionwith a recycling process cycle, the range of the respectively visiblesurface 36 and 38, respectively, of the respective marking 24 and 26,respectively, is not altered.

In contrast with this, the second embodiment, illustrated in FIG. 3,shows a marking 26' with step-shaped cross-section of the layer with aremelt structure 30'.

This layer with a remelt structure 30' is divided up into an outerregion 30a' having the thickness d 1 and an inner region 30b' having thethickness d 2 which is, for example, a multiple of the thickness d 1.

In this embodiment, when the layer with a remelt structure 30' is wornaway, for example, after several recycling process cycles, by the amountof layer thickness d 1, the size of the surface 38' has then alteredbecause the wearing-away has caused the outer regions 30a' of the layerwith a remelt structure to become worn away and only the inner regions30b' with a thickness of d 2 minus d 1 are left. Thus, the marking 26'is still present but has a smaller surface which corresponds to theinner region 30b'.

The thickness d 1 of the layer with a remelt structure 30' may be soselected that it is worn away, for example, after two recycling processcycles and so the number of recycling process cycles which therespective bracket has undergone is immediately discernible from thesize of the surface 38'.

In accordance with the invention, the thicknesses d, d 1, d 2 of thelayers with a remelt structure 30, 30' are chosen in the range ofapproximately 0.1 μm to 0.5 μm. A layer with a remelt structure 30, 30'having a thickness d, d 1, d 2 of 0.1 μm, as a rule, withstandsapproximately one recycling process cycle and is worn away after such arecycling process cycle. In contrast, a layer with a remelt structure30, 30' having a thickness d, d 1, d 2 of approximately 0.5 μm can betermed as recycling-resistant because such a layer would only be wornaway after approximately five recycling process cycles and, as a rule,five recycling process cycles are not conceivable for a bracket.

The above description of the marking of an inventive bracket applies inlike manner to the markings of bands and buccal tubes.

We claim:
 1. An orthodontic aid comprising a metallic body having anouter surface with indicia consisting essentially of a remelt structureof the same material as said metallic body, the remelt structure of themarking area indicia having a predetermined thickness providing apermanent wear characteristic.
 2. The metallic orthodontic air accordingto claim 1 wherein said predetermined thickness of said remelt structureis at least about 0.5 μm to provide said permanent wear characteristic.3. The metallic orthodontic aid according to claim 2 wherein said remeltstructure has a rougher surface than said outer surface.
 4. A method ofproducing identifying indicia on an orthodontic aid, comprising thesteps of providing a preformed metallic orthodontic body having an outersurface, and remelting a portion of said outer surface to form indiciahaving a predetermined thickness measured from said outer surface toprovide a permanent marking on said body.
 5. The method according toclaim 4 wherein said remelting step consists essentially of heating saidorthodontic body under ambient atmospheric conditions.
 6. The methodaccording to claim 5 wherein said remelting is performed to a thicknessof at least 0.5 μm.
 7. The method according to claim 6 wherein saidremelting step is performed by a laser which heats the surface of theorthodontic body above its melting temperature for a sufficient time toeffect said remelting to said thickness.
 8. In an orthodontic appliancehaving a metallic body with an outer surface having indicia, theimprovement wherein said indicia consists essentially of a remeltstructure formed in said surface to a predetermined thickness forproviding a permanent marking on the orthodontic appliance.
 9. Theorthodontic appliance according to claim 8, wherein said predeterminedthickness is at least about 0.5 μm.
 10. The orthodontic applianceaccording to claim 8 wherein said outer surface of said body is smoothand said remelt structure is rough.
 11. In a method of marking ametallic orthodontic appliance, wherein a pre-formed metallic bodyhaving a smooth outer surface is provided, the improvement comprisingthe steps of locally heating said outer surface to remelt the metallicbody to a predetermined thickness, and advancing said local heatingrelative to said surface to remelt in the form of a legible marking theouter surface of the body.
 12. The method according to claim 11 whereinsaid local heating is performed for a time sufficient to remelt saidbody to a thickness of at least about 0.5 μm and to effect a surfacefinish which is rougher than the surface finish of the body.
 13. Themethod according to claim 12 wherein said local heating is effected bymeans of a laser beam.
 14. A metallic orthodontic aid comprising ametallic body having an outer surface and a marking on the outersurface, the marking comprising a remelt structure made of the samematerial as the outer surface, and the remelt structure of the markinghaving a wear characteristic which is substantially the same as that ofthe remainder of the outer surface.
 15. A method of producing anoptically visible surface marking on a metallic orthodontic aid, themethod comprising the steps of providing a metallic orthodontic aidhaving an outer surface, treating a portion of the outer surface toproduce a remelt structure as a marking on the outer surface, thetreating step providing a remelt structure having a wear characteristicwhich is substantially the same as that of the remainder of the outersurface.